1. Field of the Invention
The present invention relates to a surface texture measuring instrument for conducting form measurements such as roughness measurements and contour measurements, and a method of the measurement.
2. Description of Related Art
To date, surface texture measuring instruments for conducting roughness measurements on workpieces having, for instance, cylindrical and conical edge lines are known (see, for instance, document 1: JP-A-8-29153).
The surface texture measuring instrument disclosed in Document 1, which includes a driving mechanism for moving the workpiece relatively with respect to a detector, conducts a provisional measurement before conducting a main measurement and totally automatically corrects a posture of the workpiece mounted on a table to the standard posture (i.e., a posture with which the main measurement is conducted) so as to conduct positioning of the workpiece. With the instrument, a measurement can be conducted in a short time. The positioning of the workpiece exemplarily includes adjustment (auto-setting) of an elevation position of the detector in the Z-axis direction (direction orthogonal to the measurement direction of the detector) and adjustment (auto-leveling) of an inclination angle of the workpiece for the measurement direction of the detector to be parallel to a measurement target surface of the workpiece.
However, in order for the surface texture measuring instrument disclosed in Document 1 to totally automatically conduct the positioning of the workpiece, the surface texture measuring instrument is required to use a combination of a table inclination device for inclining the table and an electric column device for moving the detector in Z-axis direction, which tends to result in a large-scale system configuration of the surface texture measuring instrument. Accordingly, a wider installation space may be required or device cost may be increased.
On the other hand, for conducing a roughness measurement on a relatively small workpiece, small-size portable surface texture measuring instruments have also been known. Such a small-size surface texture measuring instrument includes: a driving unit for measuring the workpiece by moving a detector along the surface of the workpiece; and an electric unit for controlling the driving unit and processing detection signals from the detector. Such a small-size surface texture measuring instrument typically checks leveling of the workpiece manually. Manual leveling check tends to consume longer time for adjustment, and repeatability in measurements of the same point may be deteriorated. Further, when both ends of a doughnut-shaped workpiece are measured, manual leveling may result in a damage to a stylus on the distal end of the detector if the stylus falls into the opening of the doughnut shape at the time of movement to the second measurement position. Thus, measurement of plurality of positions has not been necessarily easy. Accordingly, there has been an increasing demand for small-size surface texture instruments capable of automatically conducting a positioning.